Effects of ERT on survival, VCN, absolute numbers of lymphocytes and gene-marked lymphocytes, and their function after GT. (A) Experimental schema: Ada^−/− were conditioned with 200 cGy of TBI, transplanted with transduced marrow, and either remained on ERT for the duration of the experiment (200 + 4mERT: solid line), remained on ERT for 1 month after GT (200 + 1mERT: solid line to dotted line), or did not remain on ERT after GT (200−NoERT: dotted line). Recipients were analyzed at 2, 4, 10, and 16 weeks (per arm: 2 weeks; n = 2, 4 weeks; n = 3, 10 weeks; n = 4, 16 weeks, n = 4). See Figure 2 for lymphocyte subpopulation analysis and calculation of absolute values (mean ± SEM). (B) VCN. VCN in tissue cell suspensions were measured by qPCR for vector sequence (mean ± SEM). *Significantly lower at 4 weeks than at 2 weeks (P < .05).